//分离自normalize.css
article,
aside,
details, //1
figcaption,
figure,
footer,
header,
main, //2
menu,
nav,
section,
summary { //1
  display: block;
}
// Add the correct display in IE 9-.
audio,
canvas,
progress,
video {
  display: inline-block;
}
// Add the correct display in iOS 4-7.
audio:not([controls]) {
  display: none;
  height: 0;
}
// Add the correct vertical alignment in Chrome, Firefox, and Opera.
progress {vertical-align: baseline;}
// Add the correct display in IE 10-.
// 1. Add the correct display in IE.
template, //1
[hidden] {
  display: none;
}
// Links
// 1. Remove the gray background on active links in IE 10.
// 2. Remove gaps in links underline in iOS 8+ and Safari 8+.
a {
  background-color: transparent; //1
  -webkit-text-decoration-skip: objects; //2
}
// Remove the outline on focused links when they are also active or hovered
// in all browsers (opinionated).
a:active,a:hover {outline-width: 0;}
// Text-level semantics
// 1. Remove the bottom border in Firefox 39-.
// 2. Add the correct text decoration in Chrome, Edge, IE, Opera, and Safari.
abbr[title] {
  border-bottom: none; //1
  text-decoration: underline; //2
  text-decoration: underline dotted; //2
}
// Prevent the duplicate application of `bolder` by the next rule in Safari 6.
b,strong {font-weight: inherit;}
// Add the correct font weight in Chrome, Edge, and Safari.
b,strong {font-weight: bolder;}
// Add the correct font style in Android 4.3-.
dfn {font-style: italic;}
// Correct the font size and margin on `h1` elements within `section` and
// `article` contexts in Chrome, Firefox, and Safari.
h1 {
  font-size: 2em;
  margin: 0.67em 0;
}
//  Add the correct background and color in IE 9-.
mark {
  background-color: #ff0;
  color: #000;
}
// Add the correct font size in all browsers.
small {font-size: 80%;}
// Prevent `sub` and `sup` elements from affecting the line height in
// all browsers.
sub,sup {
  font-size: 75%;
  line-height: 0;
  position: relative;
  vertical-align: baseline;
}
sub {bottom: -0.25em;}
sup {top: -0.5em;}
// Embedded content
// Remove the border on images inside links in IE 10-.
img {border-style: none;}
// Hide the overflow in IE.
svg:not(:root) {overflow: hidden;}
// Grouping content
// 1. Correct the inheritance and scaling of font size in all browsers.
// 2. Correct the odd `em` font sizing in all browsers.

code,kbd,pre,samp {
  font-family: monospace, monospace; //1
  font-size: 1em; //2
}
// Add the correct margin in IE 8.
figure {margin: 1em 40px;}
// 1. Add the correct box sizing in Firefox.
// 2. Show the overflow in Edge and IE.
hr {
  box-sizing: content-box; //1
  height: 0; //1
  overflow: visible; //2
}